The pair are believed to have joined the grim toll of Jang's aides - eight are believed to have been executed since the purge, Yomiuri Shimbun added.
And reports suggest that the day after the execution, Ministry of State troops arrived in the Pyongchong area of Pyongyang and took away hundreds of people.
In North Korea family members of people found guilty of crimes are often punished.
And in this case it is believed that the family members have been taken to political prison camps.
According to The Sunday Telegraph a source told the Daily NK newspaper, which is run by defectors of the regime, that they believed even relatives living away from Pyongyang were not safe under the circumstances.
They also told the newspaper that close relatives as well as distant family members were taken away, including relatives of Song-Thaek's father.
Kim Jong Un's former mentor Mr Song-Thaek was charged with 24 offences.
These included abusing his position of power and "dreaming different dreams" to the regime.
North Korea stunned the world by announcing the execution of the man once seen as the dictator's political regent.
His death marks the biggest political upheaval since the 30-year-old inherited power.
The Kim dynasty has ruled the isolated country for more than six decades.
Mr Song-Thaek is the husband of Jong Un's biological aunt, the sister of his father Kim Jong Il.
The source added: "Jang's crimes are 'anti-party, counter-revolutionary factionalism', so of course they will have to say that his family challenged the system.
"For this reason, severe punishment awaits."
Was execution a business row over coal?
Agents at South Korea's National Intelligence Service have a number of theories about the purge, which many believe was the chilling final act of a power struggle.
But Jeong Chung-rae, a lawmaker from the United Democratic Party, said the head of the agency, Nam Jae-joon, played down the theory of a simple power grab.
Jang's death may have been ordered because he had acted outside his authority over business deals involving the export of the secretive nation's coal - an abundant and lucrative resource - angering some officals in other departments.
Jang was purged for violating the supreme leadership, according to the NIS report,' Jeong said, CNN reported.
North Korea state media has made some vague references to corrupt business practices by Jang when they extensively listed his crimes.
- Daily Mail
